ECE 476 – Power System Analysis Fall 2012
Homework 1
Due Date: Thursday September 6, 2012 Reading: Chapters 1 and 2 of GS&0
Problem 1. With|V|= 100 V, the instantaneous powerp(t) into a network N has a maximum value 1707 W and a minimum value of -293 W.
1. Find a possible seriesRLcircuit equivalent to N. 2. FindS =P +jQ intoN.
3. Find the maximum instantaneous power intoL and compare withQ.
Problem 2. A certain 1φ load draws 5 MW at 0.7 power factor lagging. Determine the reactive power required from a parallel capacitor to bring the power factor of the parallel combination up to 0.9.
Problem 3. A 3φ load draws 200 kW at a PF of 0.707 lagging from a 440-V line. In parallel is a 3φ capacitor bank that supplies 50 kVAr. Find the resultant power factor and current (magnitude) into the parallel combination.
Problem 4. A 1φload draws 10 kW from a 416-V line at a power factor of 0.9 lagging.
1. FindS =P +jQ.
2. Find|I|.
3. Assume that 6 I = 0 and find the instantaneous power p(t).
Problem 5. A small manufacturing plant is located 2km down a transmission line, which has a series reactance of 0.5 Ω/km. The line resistance is negligible. The line voltage plant is 4806 0 V (rms), and the plant consumes 120 kW at 0.85 power factor lagging. Determine the voltage and power factor at the sending end of the transmission line by using:
1. A complex power approach.
2. A circuit analysis approach.
